From patchwork Wed Jul 29 07:34:10 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin Sperl X-Patchwork-Id: 6890121 Return-Path: X-Original-To: patchwork-linux-spi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id EF71CC05AC for ; Wed, 29 Jul 2015 07:34:56 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 1E5E3207CC for ; Wed, 29 Jul 2015 07:34:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B5183202E9 for ; Wed, 29 Jul 2015 07:34:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752023AbbG2Hey (ORCPT ); Wed, 29 Jul 2015 03:34:54 -0400 Received: from [212.186.180.163] ([212.186.180.163]:55834 "EHLO cgate.sperl.org" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751621AbbG2Hey (ORCPT ); Wed, 29 Jul 2015 03:34:54 -0400 Received: from raspb.intern.sperl.org (account martin@sperl.org [10.10.10.32] verified) by sperl.org (CommuniGate Pro SMTP 6.1.2) with ESMTPSA id 6341100; Wed, 29 Jul 2015 07:34:22 +0000 From: kernel@martin.sperl.org To: Mark Brown , Stephen Warren , Lee Jones , linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, noralf@tronnes.org Cc: Martin Sperl Subject: [PATCH] spi: bcm2835: fix overflow in calculation of transfer time Date: Wed, 29 Jul 2015 07:34:10 +0000 Message-Id: <1438155250-14476-1-git-send-email-kernel@martin.sperl.org> X-Mailer: git-send-email 1.7.10.4 Sender: linux-spi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org X-Spam-Status: No, score=-8.3 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Martin Sperl This resulted in the use of polling mode when other approaches (dma or interrupts) would have been more appropriate. Happened for transfers longer than 477 bytes. Reported-by: Noralf Tronnes Signed-off-by: Martin Sperl --- drivers/spi/spi-bcm2835.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index c9357bb..e7874a6 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -480,7 +480,7 @@ static int bcm2835_spi_transfer_one_poll(struct spi_master *master, struct spi_device *spi, struct spi_transfer *tfr, u32 cs, - unsigned long xfer_time_us) + unsigned long long xfer_time_us) { struct bcm2835_spi *bs = spi_master_get_devdata(master); unsigned long timeout; @@ -531,7 +531,8 @@ static int bcm2835_spi_transfer_one(struct spi_master *master, { struct bcm2835_spi *bs = spi_master_get_devdata(master); unsigned long spi_hz, clk_hz, cdiv; - unsigned long spi_used_hz, xfer_time_us; + unsigned long spi_used_hz; + unsigned long long xfer_time_us; u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS); /* set clock */ @@ -573,9 +574,10 @@ static int bcm2835_spi_transfer_one(struct spi_master *master, bs->rx_len = tfr->len; /* calculate the estimated time in us the transfer runs */ - xfer_time_us = tfr->len + xfer_time_us = (unsigned long long)tfr->len * 9 /* clocks/byte - SPI-HW waits 1 clock after each byte */ - * 1000000 / spi_used_hz; + * 1000000; + do_div(xfer_time_us, spi_used_hz); /* for short requests run polling*/ if (xfer_time_us <= BCM2835_SPI_POLLING_LIMIT_US)